Voltage regulating system



Sept. 20, 1949. L. G. TUBBS 2,482,522

VOLTAGE REGULATING SYSTEM Filed May 7, 1946 WITNESSES; INVENTOR 4%.Zexfer G fz/bs.

w m I tive reactance of the Patented Sept. 20, 1949 ultrrizo STATESPATENT OFFICE VOLTAGE REGULATING SYSTEM Lester G. Tubbs, Pittsburgh,Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh,Pa., a corporation of Pennsylvania Application May 7, 1946, Serial No.667,755

2 Claims. (01. ass-s1) This invention relates to regulating systems andin particular to regulating systems having a stabilizing network.

Heretofore, the output of different static type regulatorshas beencorrected for voltage drop due to an inductive loadby employing acapacitor connected in series circuit in the output circuit, thecapacitor being so dimensioned that its capacity reactance willcompensate for the inducregulator. Correction for error in the outputvoltage caused by frequency variation has also been obtained by the useof a tuned reactor and capacitor connected in series directly in theoutput circuit, such correction being inproportion to the inductiveportion of the load.

compensating or stabilizing elements is too great for economicoperation, and it has been impossible to obtain simultaneouscompensation for both frequency error and the drop due to the inductiveload where both types of error occur simultaneously.

An object of this invention is to provide in a regulating system havinga static regulator for supplying an inductive load, for a stabilizingnetwork disposed for economic operation to simultaneously compensate forfrequency changes and for voltage drop in the regulator due to theinductive load.

Other objects of this invention will become apparent from the followingdescription taken in conjunction with the accompanying drawing, thesingle figure of which is a diagrammatic view of circuits and apparatusillustrating a regulating system embodying the stabilizing network inaccordance with this invention.

Referring to the single figure of drawing, this invention is illustratedby reference to the regulating'system comprising the static regulator isupplied by conductors l2 and i4 from a source (not shown) to supply aninductive load 1'6. There are many different types of static regulatorsavailable on the openmarket, and this invention is therefore not to belimited to the use of any particular type of static regulator. Theregulator l0 illustrated in the drawing is of well known construction,being sold at the present time on the open market and being shown forpurposes of illustration only.

The static regulator Ill illustrated comprises a two-winding reactor itconnected in circuit-with a part of the winding of a single windingreactor 20 provided with a highly saturated. core, a capacitor 22 beingconnected in series circuit with the winding of reactor 20. With thisconstruction, as the supply voltage varies, the exciting current of thereactor It varies greatly to vary the voltage drop in the reactor it tocompensate for line voltage changes, the capacitor 22 functioning tosupply a portion of the exciting current of reactor whereby a lowercurrent change therein produces a higher percentage change in thereactor I8.

One of the. output terminals of the regulator III is connected byconductor 24 to one side of the load I6, the other output terminal ofthe regular In being connected by conductor 26 to a termial of theprimary winding 28 of an autotransformer 30, the other terminal of theprimary winding being connected by conductor 32 to the other side of theinductive load It. The primary winding 28 of the transformer is thusconnected directly in series circuit relation between the regulator l0and the inductive load It.

As illustrated, a reactor 34 and a capacitor 36 are connected in seriescircuit relation with each other and are disposed to be supplied by thesecondary winding 38 of the transformer 30. The reactor 34 and thecapacitor 36 are carefully selected so that as supplied through thetransformer 3!! simultaneous compensation will be obtained for frequencyerror and for any change in the reactance of the regulator l0 occasionedby reason of the inductive load supplied.

Thus, the capacitor 36 in series circuit with the reactor 34 is soselected or dimensioned that at the normal frequency for the system, thecapacitor reactance is more than that necessary for cooperating with theinductive reactance of reactor 34 to balance therewith and compensatefor frequency changes from the normal. The excessive capacitor reactanceover that needed for frequency compensation is utilized to compensatefor the inductive reactance of the regulator I'll due to the inductiveload supply.

Since the reactor 34 and the capacitor 36 are connected in seriescircuit relation with each other, the voltage drops across theseelements are in opposition. It is therefore apparent that thetransformer 30 is quite small, being only of suillcient size to produceenough energy to supply the difl'erence in the voltage drops across theseries connected reactor and capacitor A small step-up autotransformeris satisfactory for transmitting the required corrective volts.

The network utilized in the system referred to hereinbefore isespecially adapted for use in low voltage circuits, such as outputcircuits of the neighborhood of -120 volts where very little energy canbe spared in effecting compensation.

The elements utilized to eil'ect the simultaneous compensation describedare all of standard design, and as a minimum of apparatus is required,it is appreciated that the system is economical in obtaining theeflicient simultaneous compensation for frequency errors and voltagedrop of the regulator due to inductive load.

I claim as my invention:

1. In a regulating system having a static voltage regulator disposed tosupply an inductive load, the combination comprising, a transformerhaving its primary winding connected in series circuit relationbetweenthe regulator and the load, and a reactor and a capacitor connected inseries circuit relation disposed to be supplied by the transformerwhereby the voltage drops across the reactor and capacitor are inopposition, the transformer being of sui'flcient size to produce onlyenough energy to supply the difference in the voltage drops across theseries connected reactor and capacitor, the reactor and capacitor beingselected to cooperate to compensate for frequency changes with thecapacitor being of suihcient capacity to also compensate for theinductive reactance of the regulator due to the inductive load supplied.

2. In a regulating system having a static voltage regulator disposed tosupply an inductive load, the combination comprising, an autotranaformerhaving a primary winding and a secondary winding, the primary winding ofthe transformer being connected in series circuit relation between theregulator and the load, and a reactor and a capacitor connected inseries circuit relation across the secondary winding of the transformer,the capacitor having a capacity reactance suiiicient to cooperate withthe reactance of the reactor to compensate for changes in line frequencywhile simultaneously therewith also compensating for the inductivereactance oi the static regulator due to the inductive load supplied.

LESTER G. 'I'UBBB.

REFERENCES CITED The following references are of record in'the file ofthis patent:

Short Jan. 16, 1945

